Unmarked DD 20261102T213439Z-60820 Guest: A good membrane shines. A tired one goes matte DD Host: Today: why a membrane holds for years, and what gives it away a week before it goes. DD Host: So why does it matter? Unmarked DD 20261102T213439Z-60820 Guest: So that, that's the b- big question. it matters because the, membrane holds. DD Host: Right. And then what? Unmarked DD 20261102T213439Z-60820 Guest: Then it breaks. The water finds the weak point and it goes through all at once. DD Host: How long does that take? Unmarked DD 20261102T213439Z-60820 Guest: Seconds, once the first crack opens. Before that it can hold for years. DD Host: And when it does break, can you see it coming? Unmarked DD 20261102T213439Z-60820 Guest: Sometimes. The surface goes soft first, and you can feel it give under your thumb. That is the warning most people miss. DD Host: So what do you tell them to look for? Unmarked DD 20261102T213439Z-60820 Guest: Look for the dull patch. A good membrane shines. A tired one goes matte a week before it fails. DD Host: That is a useful rule. Unmarked DD 20261102T213439Z-60820 Guest: It is the only one I trust. DD Host: So look for the dull patch. Thanks for listening.